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[1] The formation of organic nitrates during the oxidation of the biogenic hydrocarbon isoprene can strongly affect boundary layer concentrations of ozone and nitrogen oxides (NO x = NO + NO 2). We constrain uncertainties in the chemistry of these isoprene nitrates using chemical transport model simulations in conjunction with observations over the eastern(More)
[1] We use observations from two aircraft during the ICARTT campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of regional sources, chemical evolution, and export of NO x. The boundary layer NO x data provide top-down(More)
The yields of organic nitrates and of secondary organic aerosol (SOA) particle formation were measured for the reaction NO 3 +β-pinene under dry and humid conditions in the atmosphere simulation chamber SAPHIR at Research Center Jülich. These experiments were conducted at low concentrations of NO 3 (NO 3 +N 2 O 5 <10 ppb) and β-pinene (peak∼15 ppb), with no(More)
Eight distinct hydroxy nitrates are stable products of the first step in the atmospheric oxidation of isoprene by OH. The subsequent chemical fate of these molecules affects global and regional production of ozone and aerosol as well as the location of nitrogen deposition. We synthesized and purified 3 of the 8 isoprene hydroxy nitrate isomers:(More)
[1] We implement a new isoprene oxidation mechanism in a global 3-D chemical transport model (GEOS-Chem). Model results are evaluated with observations for ozone, isoprene oxidation products, and related species from the International Consortium for Atmospheric Research on Transport and Transformation aircraft campaign over the eastern United States in(More)
A strong temperature dependence of oxygen K-edge x-ray absorption fine structure features was observed for supercooled and normal liquid water droplets prepared from the breakup of a liquid microjet. Analysis of the data over the temperature range 251 to 288 kelvin (-22 degrees to +15 degrees C) yields a value of 1.5 +/- 0.5 kilocalories per mole for the(More)
Laboratory studies have established a number of chemical pathways by which nitrogen oxides (NO(x)) affect atmospheric organic aerosol (OA) production. However, these effects have not been directly observed in ambient OA. We report measurements of particulate organic nitrates in Bakersfield, California, the nighttime formation of which increases with NO(x)(More)
The release of NO and NO2 from frozen aqueous NaNO3 irradiated at 313 nm was studied using time-resolved spectroscopic techniques. The kinetic behavior of NO and NO2 signals during on-and-off illumination cycles confirms that NO2 is a primary photoproduct evolving from the outermost ice layers and reveals that NO is a secondary species generated deeper in(More)